This invention relates to a subband coding device for use in subband coding a digital device input signal into a subband coded signal.
In the manner which will later be described in more detail, a conventional subband coding device comprises a bank of first through N-th band-pass filters for band-limiting the device input signal into first through N-th band-limited signals having first through N-th frequency bands which are different in frequency from one another, where N represents a predetermined natural number. The device input signal represents original signal samples which are sampled at signal sampling instants and are variable either in a one-dimensional space, namely, along a time axis, or in a two-dimensional space, namely, dependent on signal points in each signal plane.
First through N-th downsampling circuits are used to downsample the first through the N-th band-limited signals into first through N-th sequences of subband samples. First through N-th coders are used to encode the subband samples of the first through the N-th sequences individually into first through N-th coded signals. A multiplexer is used to multiplex the first through the N-th coded signals into the subband coded signal.
Such a subband coding device is for coding the device input signal into the subband coded signal with a high coding efficiency. The present inventor has, however, found it possible to make the subband coding device of the type described have an astonishingly high encoding efficiency.